Pipe clamps are commonly used to join variously structured pipes and other tubular bodies in exhaust systems. To be effective, a joint between the pipes should provide a fluid-tight seal, should maintain an acceptable leak rate, and should have good resistance against axial separation. One type of pipe clamp is a band clamp which is used with telescopically overlapping pipes, and another type is a pipe coupler which is used with end-to-end abutting or closely abutting pipes. Both types typically include a band to be placed and tightened over the pipes, and both types can include a sleeve, a gasket, or both to be placed and tightened over the pipes beneath the band. The sleeve can be a split sleeve with an open loop structure having confronting circumferential ends. The confronting ends can sometimes have a tongue-and-groove construction. Examples of split sleeves with and without tongue-and-groove constructions are taught in U.S. Pat. Nos. 7,520,539, 7,410,192, 7,252,310, 7,025,393, and 6,758,501, all owned by the assignee of the present patent application.